A 19th century postage stamp sold for a record $9.5m – almost one billion times its original face value – at an auction at Sotheby’s in New York on Tuesday evening.

The 1856 British Guiana one-cent magenta, regarded by collectors as the world’s most famous rare stamp and described as the Mona Lisa of the philately world, was sold to an anonymous bidder in just two minutes.

It has now set a record each of the four times it has been sold at auction, and is the most valuable object ever sold, by size and weight.

David Redden, Sotheby’s Vice-chairman, said: “We are thrilled with tonight’s extraordinary, record-setting price of $9.5 million – a truly great moment for the world of stamp collecting. That price will be hard to beat, and likely won’t be exceeded unless the British Guiana comes up for sale again in the future.

“I have to say I’m a little sad to see it go – when I was eight years old this was the most precious object in the entire world, and I never dreamt I would have it in my hands.”

The previous record for a single stamp sold at auction was $2.3m, at 1996 prices: the Swedish Tre skilling yellow was last officially sold in Zurich for SFr2.88m.

The British Guiana one-cent magenta is the only surviving example of its kind.

It had been bought in 1980 by John du Pont, the chemical industry millionaire, sportsman and collector who kept it locked away in a vault. Du Pont was jailed for 30 years for shooting dead an Olympic gold-medal winning wrestler in 1996 and died in 2010. The stamp was sold on Tuesday night as part of his estate.

Printed in black on magenta paper, the British Guiana stamp carries the image of a three-masted ship and the former colony’s motto in Latin: “We give and expect in return.” It was produced in Georgetown, now Guyana, after a shipment of stamps was delayed from London, threatening to disrupt the postal service.

The stamp’s first owner, Vernon Vaughan, a 12-year-old Scottish schoolboy, found it among family papers in 1873. He sold it for a few shillings to fellow Scot Neil McKinnon to buy more stamps. By 1980 its price had reached £402,000, equivalent to £1.5m today, when du Pont bought it.

It has not been on public view since 1986, when it was exhibited at the Ameripex stamp show in Chicago.

Low interest rates have sparked renewed interest in stamp collecting, often thought to be a pastime for boys, geeks or canny pensioners.

Many visitors to the Spring Stampex fair at the Business Design Centre in Islington, north London, this year were hunting for stamps to add to their albums as a “nest-egg” for the future.

It is not a way to get rich quick, said one seasoned dealer, but investors can expect steady appreciation over five, 10 or 15 years, with relatively little downside risk from economic or political shocks.

The solid returns were evident among US investors, said George Holschauer, a specialist in British Empire and rare stamps. He concentrates on building collections to order that often become multi-generational holdings for families.

Graham Childs, organiser of Stampex and secretary of the 400-member Philatelic Traders Society, said 60 years of exhibitions had built a sound trading base which embraced tiny specialist vendors as well as the leading auction houses like Spink and Sotheby’s.

“We are poor in relation to the art world but the investment side is quite strong and this summer’s Sotheby’s sale of the British Guiana magenta will stir much interest.”

Plain stamp’s colourful past

From schoolboy discovery sold for six shillings to world record, the one-cent magenta has had a colourful past.

●1856 A shipment of stamps was delayed, threatening disruption of postal services. Postmaster commissions a local contingency supply: the one-cent magenta, a four-cent magenta and four-cent blue

●1873 Vernon Vaughan, a British schoolboy living in Demerara finds the stamp among his uncle’s papers

●1873 Sold to another collector, Neil McKinnon, for six shillings as there was no record of it in Vaughan’s stamp catalogue

●1878 The one-cent magenta enters the UK and shortly after is bought by Count Philippe la Renotière, perhaps the greatest collector. His collection was seized in 1917 by the French state as war reparations after he donated it to the Postmuseum in Berlin. The stamp was bought by textile magnate Arthur Hind for its first auction price record of $35,000. He reportedly outbid three kings for it, including Britain’s King George V – today it remains the only rare stamp not in the Queen’s collection. According to collecting legend, when a second one-cent magenta came into Hind’s possession, he set fire to it with his cigar to protect the value of the one he already owned. Next to own it was Australian engineer Frederick T Small, then a Pennsylvanian consortium headed by Irwin Weinberg

●1980 bought by John du Pont. He paid $935,000 for it, the object’s most recent record-setting price. Left locked in a bank vault after du Pont was jailed for 30 years for murder

●2014 Sold to an anonymous bidder at Sotheby’s in New York after just two minutes, setting a new world record price

●The stamp has featured in a Donald Duck comic book, 1952’s The Gilded Man, and a John D. MacDonald thriller novel, 1996’s The Scarlet Ruse.